Drill bit and method and apparatus for making same



Feb. 17,1970 Q .1. D. DITSON, v 3,495,670

DRILL BIT, AND METHOD AND APPARATUS FOR MAKING- SAME Original Filed May9, 1966 2 SheetS -Sheet 1 mu 7 v P I v Feb. 17, 1970 a J. D, DITSON3,495,670

DRILL BIT AND METHOD AND APPARATUS FOR MAKING SAME Original Filed ma 9,1966 2 Sheets-Sheet 2 "gr-w I.

1 10. D/TSO/V INVENTOR.

United States Patent US. Cl. 175410 9 Claims ABSTRACT OF THE DISCLOSUREA method and apparatus for forming button type drill bits by forcingcarbide inserts into a bit blank. The invention permits the manufactureof button him without pre-drilling holes for the carbide inserts. Thebuttons are pushed into the bit blank by means of a hydraulic press.

This application is a continuation of Ser. No. 548,766, filed May 9,1966, now abandoned.

This invention relates to a method and apparatus for forming a bit fordrilling rock. More particularly, this invention relates to a method andapparatus for inserting buttons in a button bit.

A button bit is known by those having ordinary skill in the art of rockdrilling to be a percussion bit having a plurality of tungsten carbideor other hard material inserts or buttons which project out of thatportion of the bit which contacts the rock face.

Prior methods of inserting carbide inserts into blanks comprise shrinkfit or press fit. Silver brazing has also been used but this method hasbeen abandoned to a great extent. In the press fit and shring fitmethods, it is necessary to drill a hole in the bit body or blank beforethe carbide button can be inserted. In press fit, a hole is drilled andthen the button or insert is forced into the hole. In shrink fit, a holeis drilled into the blank, the blank is heated increasing the size ofthe hole and the button is inserted into the hole. When the blank cools,the button is held firmly in place.

Since both the press and shrink fit methods depend on the stretch of ahole in the bit body, accurate control of size of both the hole and thecarbide is necessary to avoid overstresses. Production of multiple holesto the required tolerance and precision is expensive. Slight errors cancause the entire bit to be rejected. In addition to the necessity ofthe'holes being accurately located and sized, the carbide inserts mustalso be of accurate diameter. Since the blank bit is a relatively softmaterial and the buttons are tungsten carbide, it has been discoveredthat the buttons may be pushed into the blank without first drilling ahole.

It is, therefore, the principal object of this invention to provide amethod of forming drill bits which overcomes the above objections.

It is another object of this invention to provide a method of insertingbuttons into a blank which reduces the number of operations necessary.

It is a further object of this invention to provide novel apparatus forforcing inserts into a blank.

In general, these objects are carried out by providing a housing whichis open on one side and has a press in the upper portion. Attached tothe press is a setter means which has an insert feeding means attachedthereto. A jig for holding the bit blank is located on the floor of thehousing. In order to insert a button into a solid metal blank, the blankis first heated and then held in the jig. A button is held adjacent theblank by placing the setter means and bit feeding means adjacent theblank. The press is operated and an insert or button is forced into theblank in the desired location to a depth such that the insert extendsabove the bit face a predetermined distance. When the insert is in theblank as far as is desired, the blank around the insert is crimped toprevent the insert from coming out. The blank is then cooled.

These and other objects will become apparent from the followingdescription and drawings in which:

FIG. 1 is a perspective view of simplified apparatus for carrying outthe method of this invention with certain parts broken away for purposesof clarity;

FIG. 2 is an elevational cross-section of a portion of FIG. 1;

FIG. 3 is a view similar to FIG. 2 showing the button being forced intothe blank;

FIGA is a detail showing the blank crimped around the insert; and

FIGS. 5 and 6 are details showing a different shape insert being forcedinto a bit blank.

Referring to the drawings, the simplified apparatus for forcing atungsten carbide or other hard material button into a bit blankcomprises a housing generally designated at 1. The housing is secure-dto a plate 76 by any suitable means such as welding 79. One side of thehousing is open, as at 2, to provide a viewing area and an entrance forthe other apparatus. The upper portion 3 of the housing 1 includes acylinder 4 having fluid supply connection 5 and :6. The cylinder 4 isclosed at the end by a plug 7 which threadedly engages the cylinder. Theplug is sealed by an O-ring. Slidably mounted in the cylinder 4 is apiston 11 having :a sealing ring 12. A ram 13 is attached to the pistonand moves through and opening 9 in the plug 7. An O-ring 10 in theopening 9 prevents leakage of fluid through the opening 9. The end ofthe ram 13 opposite to the piston :11 is enlarged as at 14.

A setter, generally indicated at 20, is attached to the ram. The settercomprises a cylindrical member 21 which has an axial bore 22thereth-rough, as shown in FIG. 2. The bore 22 is counter-bored at 23 soas to receive the enlarged end 14 of the ram. The set-tor 20 is held inplace on the ram by a set screw 15 or other suitable means. The bore 22is narrowed at the lower end 24 to provide a seat or stop 25. A plunger26 having a shoulder 27 at its upper end is slidably mounted within thebore 22. The shoulder 27 is of such a size that it will rest on the stop25. The plunger 26 has an axial bore 28 of constant diameterthereth-rough.

A spindle, generally indicated at 30, has a reduced diameter portion 31which is adapted. to slidingly fit in the bore 28 of the plunger. Theupper portion of the spindle has a shoulder 32. Between the shoulder 32of the spindle and the upper portion of the plunger 26 there is a spring40, the purpose of which will be explained hereinafter.

There is a feeding means which includes a hollow tube 35 fitted to theend of the plunger 26. The outer end of the tube 35 extends through anopening in the housing 1. The tube 35 has an opening 36 through Whichthe plunger extends. The plunger 26 has an opening 29 which is axiallyaligned with the opening in the tubular member 35. The member 35 fitsonto the plunger 26 and is secured thereto by any suitablle means sothat it abuts a shoulder 41 and the end of the plunger extends beyondthe bottom of the tubular member, as is best shown in FIGS. 2 and 3.

The feeder tube 35 is of such a size that a plurality of tungstencarbide buttons or inserts 50 will fit into it, as clearly shown inFIGS. 2 and 3. A rod 37 is slida'bly mounted within the member 35 and isbiased forward against the inserts 50 by a resilient member 38 so thatthe buttons 50 will be forced into the bore 28 one at a 3 time. The endof the rod 37 has a notch 39 for holding the resilient member 38. When abutton is pushed into the bore 28, it is prevented from falling out by aretaining ring 42. The button is now axially aligned with the spindle30.

-A metal bit blank 60 is held in a cylindrical member 72. Thiscylindrical member is held in a circular opening 71 of a jig 70. Theforward edge of the jig is beveled at 73 so that, when it is desired toinsert buttons into the gauge or edge 61 of the blank, the bit may betilted to the proper angle. The jig fits into a plate 74 which has asquared opening 75 therein. The jig 70 may be moved so that when onebutton is in place, the blank may be repositioned and a second buttonmay be put in. The plate 74 is fastened to a second plate 76 by anysuitable means such as screws 77. The plate 76 is secured to asupporting table (not shown) by any suitable means such as bolts 78.

METHOD A metal bit blank 60 is heated to the required temperature. Thistemperature depends on the amount of force used to push the button intothe blank. In one test performed with a small hydraulic press, it wasfound necessary to heat the bit to around l700 Fahrenheit. If a largerpress is used, the heat may be reduced. The heated blank is placed inthe cylindrical member 71 which is then placed in the jig 70. The jig 70is then located in the desired position below the setter 20 so that thebutton will be inserted in the proper location.

An insert or button made of material harder than the blank is pushedinto the bore 28 of the plunger 26 by the rod 37 and rests on theretaining ring 42.

Hydraulic fluid under pressure is supplied to cylinder 4 through theconnection 5 and the piston 11. Ram 13 and setter are lowered until theend 43 of the plunger contacts the face of the bit blank 60. The lowerside of the cylinder is exhausted through connection 6. As morepressurized fluid is applied to the upper side of the piston 11, thesetter 20 and spindle continue to be lowered but the plunger 26 remainssubstantially stationary against the bit face. The plunger is loweredbecause the ram has positive contact with it, but the spindle is notlowered because most of the movement of the ram is absorbed by thespring 40. The setter moves downward and the spindle 30 moves downwardthrough the bore 28 of the plunger.

The rounded surface 44 on the end of the spindle 30 contacts the roundedsurface of the button. As the ram 13 and spindle continue to movedownward, the spring is compressed and the spindle begins to push thebutton into the bit blank 60. This step is clearly shown in FIG. 3.Continued downward movement pushes the insert farther into the blank.Because the spring 40 is being compressed, the force of the ram is beingtransferred to the plunger 20 and thus the plunger moves downward. Thedownward movement of the plunger 26, while the button is being pushedinto the blank, crimps the bit face around the edge of the button 50, asis best shown in FIG. 4.

The downward movement of the press is limited so that the insert extendsabove the face of the blank a predetermined distance. The force of thehydraulic press is such that the button is pushed into the blank thedesired depth, i.e., enough of the button 50 projects above the blankface to do the proper drilling. The press is designed so that it hasinsufiicient force to push the button any farther into the blank. Theram 13 cannot be lowered any farther.

As the blank is cooled, the metal of the blank shrinks around the#button and this, combined with the crimping, holds the button firmly inplace.

The piston 11 is then raised along with the ram 13 and setter 2G bysupplying hydraulic fiuid to the lower side of the piston through theconduit 6. As the setter is 4 raised, the spring 40 biases the plungeraway from the spindle 30, and the portion 31 of the spindle is raisedpast the opening 29, and another button is forced into the bore 28 andready to be set. The jig and blank are then moved to a new locationrelative to the setter, and the next button is ready to be inserted.

With the method of this invention, it is possible to insert other shapebuttons such as the tapered button shown in FIGS. 5 and 6. When thisbutton is inserted, the bit blank tends to open up as large as thelargest diameter of the insert 51. This opening 62 is best shown in FIG.5 which shows the button being forced into the blank but before anycrimping action. The opening 62 is closed by the crimping action, asclearly shown in FIG. 6.

Although a simplified apparatus has been shown for carrying out themethod of this invention, other apparatus may be used. If desired, aforging press may be used rather than a simple hydraulic press. Aforging press will hammer the buttons into place rather than push themin. More sophisticated setting and feeding devices may be used.Additionally, it is considered that it is within the scope of thisinvention to provide a plurality of setter means and presses so thatmany or all of the buttons may be inserted into the bit blank at thesame time rather than at one at a time.

As is readily apparent from the above description, the number of stepsrequired for inserting a button into a bit blank has been substantiallyreduced. By the method of this invention, it is not necessary topre-drill a hole in the blank although this may be done, if desired. Thenecessity of making the buttons of accurate size is reduced. All that isrequired is that the blank be properly aligned so that the button isinserted in the proper location. Alignment is only required once,whereas, in prior methods, the blank had to be properly aligned at leasttwice, once for drilling and once for inserting the button.

Having described a preferred embodiment, it is intended that thisinvention not be limited in any way except by that which is within thescope of the appended claims.

I claim:

1. The method of making a drill bit comprising the steps of:

holding a bit blank having a solid surface;

holding at least one insert adjacent the surface of said bit blank; and

forcing each insert into said bit blank so that the portion of saidinsert which is below the surface of said bit blank is substantiallycompletely surrounded by the material of said bit blank so that saidinsert is tightly held in said bit blank and movement of said insertrelative to said bit blank is prohibited.

2. The methodof claim 1 wherein each insert is forced into said bitblank until the top of the insert extends above the surface of said bitblank a predetermined distance.

3. The. method of claim 1 wherein each insert is forced into said bitblank by the application of a steady force on the insert.

4. The method in accordance with claim 2 further comprising the step ofcrimping said bit blank around the insert.

5. The method in accordance with claim 4 wherein said blank is heatedbefore the insert is forced into said bit blank.

6. Apparatus for forcing at least one insert into a bit blank to therebyform a drill bit comprising:

a first member having an axial bore therein;

spindle means mounted for reciprocating movement in said axial bore;

means for placing an insert adjacent said spindle means;

press means for acting on said spindle means to force said insert intothe surface of a bit blank; and means operable by said press means forcrimping the material of a bit blank around said insert.

5 6 7. The method of making a drill bit for drilling a hole body so thatits top projects above the surface of said bit in rock comprising thesteps of: body and that portion which is below the surface of saidholding a bit blank; bit body is supported on all surfaces by said bitbody. holding an insert which is dimensioned so that its base 9. Thedrill bit of claim 8 wherein said insert is subis larger than its topadjacent the surface of said bit stantially conical in shape.

blank; and 5 forcing said insert into said blank so that the base ofReferences Cited said insert is embedded in said bit blank and the topUNITED STATES PATENTS of said insert projects above the surface of saidbit blank and that portion of the insert which is below 1798738 3/1931Hoem the surface of said bit blank is supported on all sides 10 21212026/1938 Killgore 175 410 X 2,626,128 1/1953 Bolce 175-4l0 X Sam blank 2652 942 9/1953 Muchy 227 54 X I 8 A dnl bit for boring a hole in rockearth or the 2,990,025 6/1961 Talbert et a1 175-410X like comprising abit body and at least one hardened metal insert partially embedded insaid bit body; said insert 15 TRAVIS S MCGEHEE Primary Examiner beingdimensioned so that its base is larger in area than the cross-sectionalarea of the portion adjacent the surface US. Cl. X.R.

of said bit body said insert being embedded in said bit 76-5, 108

